second lieutenant

Definitions

from The American Heritage® Dictionary of the English Language, 4th Edition

n. The lowest commissioned rank in the U.S. Army, Air Force, and Marine Corps.

n. One who holds this rank.

from Wiktionary, Creative Commons Attribution/Share-Alike License

n. The lowest rank of a commissioned army officer, below a lieutenant.

n. The lowest rank of a commissioned officer in the United States Army, United States Air Force, or United States Marine Corps, below a first lieutenant. The rank of second lieutenant is equivalent to the naval rank of ensign.